Multiple section fluid energy drying mill



Dec. 15, 1970 STEPHANOFF 3,546,784

MULTIPLE SECTION FLUID ENERGY DRYING MILL Filed July 7, 1969 //V VE/VTOR NICHOLAS N. STEPHA NOFF A TTR/VEY United States Patent 3,546,784 MULTIPLE SECTION FLUID ENERGY 7 DRYING MILL Nicholas N. Stephanolf, Havel-ford, Pa., assignor to Fluid Energy Processing & Equipment Company, Hatfield, Pa., a corporation of Pennsylvania Continuation-in-part of application Ser. No. 703,647,

Feb. 7, 1969. This application July 7, 1969, Ser.

Int. Cl. F26b 3/10 US. CI. 34-10 ABSTRACT OF THE DISCLOSURE A fluid energy drying mill comprising at least two opposed generally annular mill portions. Solidparticles are This is a continuation-in-part of co-pending application Serial No. 703,647, filed Feb. 7, 1968.

The aforesaid application Serial No. 703,647 related to a so-called double mill wherein there are two opposed mill portions leading away from a central upstack or duct and wherein fluid nozzles were arranged angularly to project gaseous fluid toward each other in an angular direction. These angular fluid jets entrained solid particles fed into the mill and caused them to impact each other in an angular direction. The result was to eifect a grinding or pulverizing action while at the same time providing a relatively large motive force to move the pulverized particles up through the upstack and around the opposed mill portions.

In accordance with the present invention, it has now been found that the same general type of mill can be used to effect only drying with no grinding, or at least a minimum of grinding, by means of providing a central vertical fluid nozzle and selectively angled side nozzles whereby only the motive force is applied to the particles without impacts therebetween. The gaseous fluid, which may be either high or low pressure fluid, is heated, so that it not only propels the particles through the mill but also drys the particles as they move through the mill. The driest particles, being lighter, are centrifugally exhausted through exhaust ducts on the inner peripheries of the mill portions, while the less dry particles, being heavier, are centrifugally recycled back for another pass through the upstack and opposed mill portions.

FIG. 1 is a sectional view of a mill embodying the present invention.

FIG. 2 is a fragmentary sectional view showing an alternative form of the invention.

Referring now in greater detail to the various figures of the drawing wherein similar reference characters refer to similar parts, there is shown in FIG. 1 a mill, generally designated 300, comprising a right hand mill portion 302 and a left hand mill portion 304. The mill portion 302 includes a downstack 306 integral with a curved inlet chamber 308 at the bottom. A fluid nozzle 310 leads from a source (not shown) of gaseous fluid, such as air, steam, or the like, under pressure. The fluid jet issing from the nozzle 310 is arranged to intersect a stream issuing from 3 Claims a nozzle 312 connected to a source (not shown) of a suspension of solid particles.

The particles in suspension from nozzle 312 are entrained by the pressure fluid from nozzle 310 and are carried around into the chamber 308. A similar arrangement of nozzles 314 and 316 are provided in the downstack 318 of mill portion 304.

The inlet chamber 308 and a similar inlet chamebr 320, at the opposite side, are provided with a plurality of fluid inlet nozzles, respectively designated 322 and 324, in fiield communication with a manifold 326. The manifold 326 is supplied with heated fluid, such as air, steam, or the like,.under either high or low pressure, from a header 328 adapted to be connected to a source of such fluid (not shown).

The nozzles 322 and 324 are so adjustably inclined that the hot gases issuing thereform pass into the center up- A by the fluid under pressure from nozzles 310 and 314, they fall into the respective chambers 308 and 320 and are entrained by the hot fluid from the nozzles 322, 324 and 332. This hot fluid, while propelling the particles through the upstack 330 and then centrifugally around the curved elbow portions 334 and 336, also simultaneously drys the particles because of the heat. The drier particles, being lighter, pass around the inner peripheries of the mill portions 302 and 304 and are centrifugally exhausted through the respective exhaust ducts 338 adn 340. The less dry particles being heavier, centrifugally pass around the outer peripheries of the mill portions 302 and 304 and pass through the respective downstacks 306 and 318 back into the chambers 308 and 320 where they are again entrained by the hot fluid and pass through the upstack 330 for another cycle.

Although two feed means, one on each side, are shown, as at 310, 312 and 314, 316 it is possible to use only one such feed means at one side. Furthermore, it is possible to inject a solution rather than a suspension of the particles, the particles percipitating out of the solution because of rapid flash drying and/or crystallization due to the hot gas streams.

FIG. 2 shows an alternative form of the device, generally designated 400, wherein all parts which are the same as in FIG. 1 are referred to by the same reference numerals, except that they are primed. However, instead of the spray feed means such as shown at 310, 312 and 314, 316, the feed means in this form of the invention comprises a hopper 402 having a duct 404 leading into the downstack 306'. A fluid nozzle 406, connected to a source of gaseous fluid under pressure (not shown) leads into the duct 404 and propels particles fed through hopper 402 into the mill. This type of feed means is best used for wet solid materials rather than those in suspension or solution. Such materials may include particles or gel-like substances, such as calcium stearate or the like, which come out as fine particles because of the drying, and which are then dispersed by the fluid streams.

Although one feed means 402, 404, 406 is illustrated in the drawing, it is within the scope of the invention to provide a similar means at the opposite side of the mill.

By the above-described construction, there is provided a highly eflective drying mill which can take a greater load than other fluid energy drying mills and which is substantially free from any grinding action, such as would take place if the nozzles were arranged to produce crossimpacts of the particles. It is also more eifective than other drying mills because the opposed jets of heated gaseous fluid create a balanced heat flow which prevents any sudden loss of drying heat during passage through the upstack due to the rapid cooling effect of the evaporating moisture from the wet particles being dried. Such rapid cooling may be a cause of inefiective operation in a single action type of mill. Highly important is the previously mentioned dynamic barrier effect of the central stream. Furthermore, in a single action mill, it is often necessary to use several atomizing units to obtain the finest possible dispersion. By placing the spray units further apart, or at opposite sides, re-agglomeration because of premature contact is prevented.

Although only two mill portions are disclosed herein, it is possible to use any number of mill portions extending from a single central upstack.

The invention claimed is:

1. Apparatus for drying solid particles, comprising at least two generally arcuate mill portions connected by a common stack forming part of each mill portion, at least one mill portion having an inlet for feeding solid particles to be dried into the mill in a selected path and an outlet for exhausting centrifugally separated relatively dry particles from the mill, each mill portion having an inlet chamber, and a central nozzle between said inlet chambers and in alignment with said common stack, said nozzle being in fluid communication with a source of heated fluid under pressure.

2. The apparatus of claim 1 wherein each inlet chamber is provided with at least one angularly arranged nozzle connected to a source of heated fluid under pressure, said last mentioned nozzles being so inclined that they are adapted to direct fluid streams into said common stack but without intersecting each other or the fluid stream from said central nozzle. Y

3. A.method of drying solid particles which comprises feeding said particles into a mill having at least two annular paths extending from a common central path, entraining said particles in a stream of heatedfluid under pressure, said fluid being directed into said common cenr tral path in a direction to prevent impact between par- References Cited UNITED STATES PATENTS 2,297,726 10/1942 Stephanoff 34 10- 2,550,722 5/1951v Rollman -e 34 -10X 3,329,418 7/1967 Stephanoff 34-57X FREDERICK L. MATTESON, IR., Primary Examiner R. A. DUA, Assistant Examiner 

